1. Field of the Invention
The present invention relates to a composition for removing or lightening (bleaching) hair color, especially of human hair, which is mixed with an aqueous oxidation agent containing preparation immediately prior to application to hair to have its color removed or lightened.
2. Description of the Related Art
Usually oxidizing preparations are used for decolorizing or bleaching hair, which are obtained by dissolving a so-called bleaching powder (powder mixture of alkali salts and inorganic persalts, such as sodium or ammonium persulfate) in an aqueous hydrogen peroxide solution.
The use of this kind of bleaching powder, which necessarily comprises a plurality of ingredients, has many disadvantages. The different powdery ingredients thus have a tendency to separate during storage or transport because of the use of raw materials having different densities. The heavier ingredients of the powder collect in the lower portion of the powder's container, while the lighter ingredients collect in the upper portion. This un-mixing or separation has the consequence that equal portions of powder taken from different parts of the container have different chemical compositions and thus can have a different decolorizing or bleaching action. In order to counteract this separation it is necessary to shake the powder thoroughly before taking it from the container, which however the user does not usually do. A separation can also be counteracted by the use of mixed powders with very small grain size. This however has the disadvantage that those powder mixtures are inclined to generate dust, which leads to irritation of the lungs, especially when the container is opened and the powder is removed and mixed with hydrogen peroxide. Furthermore this sort of powder mixture has a large surface area because of its reduced grain size, so that an up-take of moisture occurs on opening and closing of the container. Thus a reduction of the hair decolorizing or color lightening action is promoted on account of the deactivation of the oxygen carrier.
The preparation of the ready-to-use mixture occurs by stirring the ingredients in a vessel or by mixing them together in a shaking flask. Especially shaking often involves a troublesome dust development on filling the ingredients into the shaking flask.
There already have been numerous attempts to solve this problem. Thus, in German Patent Document DE-OS 40 26 235 a mixture comprising a persulfate granulate and granulate of conventional ingredients of a bleaching agent is described instead of a bleaching powder. Of course the problem of dust generation can be eliminated by use of granulate, but the problem of separation cannot be solved in this way, since it is exceptionally difficult to prepare an individual granulate with identical and constant grain size and batch weight. Furthermore the bleaching or decolorizing action can be impaired because of the differing solubility of the individual granulates. From an economic standpoint it does not make sense to produce a mixture of several granulates instead of an individual granulate. In EP-PS 0 560 088 a powdery agent for lightening or decolorizing the hair is described in which an oil or a liquid wax is added to prevent dust formation. However dust generation cannot be eliminated completely in this manner, i.e. the resulting composition is not dust-free. Furthermore a deactivation of the oxygen carrier occurs because of the water content of the powdery raw material employed, whereby the product is unstable and its decolorizing or bleaching action is lost. Furthermore bleaching agents of this type are unsuitable for use in an applicator flask because of their specific gravity and their hydrophobic character. The powder does not sink to the bottom of the hydrogen peroxide solution and is not sufficiently wet, whereby a non-uniform mixture with a high percentage of undissolved powder is obtained, which clogs the outlet of the applicator flask. The addition of surfactants, which improve the solubility of the powder is similarly problematical, since the storability of the powder is impaired by that. Pasty two-component preparations for making a ready-to-apply pasty preparation for bleaching of human hair are described in DE-OS 38 14 356 and U.S. Pat. No. 4,170,637. In these preparations the powdery ingredients are worked into a hydrophobic base, comprising oil and wax, so that a paste results. This suspension has the disadvantage that it is somewhat inclined toward phase separation, which is observable as an oil separation. In order to prevent this an absorbing agent, for example silicic acid, is added, whereby the paste again is very solid. In DE-PS 197 23 538 pasty two component preparations were described for making a ready-to-use pasty preparation for bleaching of human hair. This preparation, besides the usual ingredients for bleaching contains a certain thickener combination. This thickener combination comprises an acrylic acid polymer and at least one polymer made from cellulose, alginate and polysaccharide, at least one mineral oil, at least one liquid, long-chain, hydrophobic fatty acid ester and at least one waxy, long-chain, hydrophobic fatty acid ester and/or synthetic beeswax substitutes. These agents are however not satisfactory in every aspect or regard in relation to their behavior at high temperatures. In DE-OS 199 09 661 the use of special bleaching agent suspensions based on ingredients that form lipogels or oleogels is disclosed.